Crystal Research and Technology最新文献

Hydroxychloroquine sulfate is a common drug for the treatment of rheumatoid arthritis. However, the disadvantage of this drug is that it needs to be taken continuously for 3–6 months to be effective and compliance of patients is poor. In this work, four new salt forms of hydroxychloroquine are successfully prepared whose crystal structures and properties are confirmed by a series of solid-state characterization methods, including infrared spectroscopy, single crystal X-ray diffraction, powder X-ray diffraction, thermal analysis, and dynamic vapor sorption analysis. The hygroscopicity, stability, equilibrium solubility, and intrinsic dissolution rate of the four new salts are also tested. The moisture absorption, solubility, and intrinsic dissolution rate of newly prepared salts are significantly reduced, and the dissolution rates of 1-hydroxy-2-naphthoate and 1,5-naphthalenedisulfonate salts are only 1/158 and 1/335 of that of the therapeutically used sulfates, respectively. It is expected that they are potentially useful to be developed into a sustained-release formulation, which can greatly improve the dosing compliance for rheumatoid arthritis treatment.

Herein stacked layers of iron selenide (FeSe₂) thin films are deposited by the physical evaporation technique and thermally annealed. An in situ monitoring of the crystallinity during the annealing process has shown that the crystallinity is reached at 100 °C. The crystallinity of the films that preferred the orthorhombic phase is enhanced with increasing annealing temperature. Evidences about the improved crystallinity are presented by the increased crystallite and grain sizes, decreased microstrain values, decreased stacking faults, and decreased defect densities with increasing annealing temperature. Optical investigations have shown impressive effect of the annealing process on the optical reflectance, optical contrast, and light absorbability. Namely, respective improvement percentages exceeding 170%, 64%, and 140% is achieved near E≈2 eV for samples annealed at 200 °C for 20 min. Both direct and indirect optical transitions are dominant in the film. In addition the annealing increased the dielectric constant in the spectral range of 1.17–4.20 eV. Maximum dielectric enhancement by 214% is reached near ≈2.10 eV. Moreover, the annealing process increases the optical conductivity and drift mobility of the FeSe₂ films. The improvement in the crystallinity that resulted in enhanced optical properties makes the thermally annealed FeSe₂ films promising for optoelectronic technology applications.

Aspirin, a commonly used pharmaceutical therapeutic pharmacological substance, exhibits cross-nucleation (intergrowth or overgrowth) of stable polymorphic Form-I over the preferably required metastable polymorphic Form-II, which creates a bottleneck issue in the solution crystallization of aspirin in most organic solvents and their mixtures. Controlling the overgrowth phenomenon is a key factor for designing the pharmaceutical drug material aspirin with desired properties. Hence, our present work chose a novel template-assisted swift cooling crystallization with selected templates like copper-wire and nylon 6/6 polymer, and also N-N-Dimethylformamide (DMF) as a solvent. The pure solution in the absence and the presence of a nylon 6/6 template in all the experimental supersaturation ranges achieves only thermodynamically stable polymorphic Form-I of aspirin with slightly different morphologies. Contrarily, the presence of a copper-wire template induces both stable and metastable polymorphs of aspirin depending on the level of supersaturation in the mother solution. The effect of templates on the nucleation kinetics of aspirin polymorphs is estimated using classical nucleation theory, and the determined values exactly match with experimental results. The polymorphic nature of the grown crystals is ascertained by powder X-ray diffraction (PXRD), single crystal X-ray diffraction (SCXRD), and differential scanning calorimetry (DSC) analyses.

A recent interest attaches to the derivatives of the (2-benzylsulfinyl)benzoic acid as inhibitors of human carbonic anhydrases (hCAs), an action that can be applied in innovative therapies. A set of crystal structures of six sulfides and six enantiopure sulfoxides related to this scaffold, taken from the literature, or derived from the work on the asymmetric synthesis of sulfinyl compounds, is investigated. The lattice energies of these structures are estimated by means of the Crystal Explorer 21 program. The weak interactions building up the crystal structures are identified, and their contributions are analyzed in comparison with the calculated lattice energies. The most stable conformations in the solid phase are identified. It is worth observing that the sulfides of the scaffold under investigation behave almost in the same manner; on the other hand, the presence of the sulfinyl group of the sulfoxides adds complexity, that shall be taken into account in future docking calculations of these molecules with the hCAs enzymes.

A new polymorph of maltol, a food and intermediate pharmaceutical material, is discovered through solution crystallization process using a mixed solvent of water and ethanol with l-menthol as an additive. It belongs to monoclinic crystal system with lattice parameters: a = 7.136(8) Å, b = 24.23(3) Å, c = 7.020(8) Å, and β = 106.22(3)°, volume =  1165 (2) Å³ and the refinement factor is R = 6.64%. With single crystal X-ray diffraction (SCXRD) data as input, the intermolecular interactions between the new polymorph of maltol is investigated through Hirshfeld surface analysis, the higher percentage of overall interaction between the polymorph (H…H) interaction, and the (O…H) interaction contributes more to the generation of new polymorph. The 2D finger print plot depicts the interactions are mainly due to the hydrogen bonds.

This study investigates the crystallization of acetaminophen (ACET) in ultrapure water and a 10 wt.% aqueous polyacrylic acid (PAA) solution using non-photochemical laser-induced nucleation (NPLIN) for the first time. Using a 532 nm nanosecond laser, two distinct crystal morphologies—rhombic and tetragonal plate-like—are formed in both solvents after adding impurities. Notably, the PAA solution showed a reduced number of crystals and slower growth rates compared to ultrapure water, suggesting that the acidic polymer modulates crystal growth. Interestingly, crystals are not induced by the laser without impurities. However, impurities like copper phthalocyanine (CuPc) or boron carbide (CB₄) enabled successful NPLIN, with CB₄ showing higher nucleation efficiency than CuPc. The study also explores how laser power affects nucleation probability and identifies potential laser energy thresholds. Experimental data on ACET crystal sizes over time are fitted to derived equations, which accurately represented trends and predicted results. The nanoparticle heating mechanism and the role of acidic polymers in affecting nucleation probability and growth rate are discussed, along with potential mechanisms for changes in crystal morphology.

Ultrapure gallium up to 99.9999%/ 99.99999% (6N/7N) purity level is a highly demanding material needed for the growth of gallium-based group III–V semiconductor compounds and optoelectronic devices. However, general extraction of gallium from Bayer liquor contains high impurity content and ultra-purification of the same cannot be accomplished by a single step. Thus, the purpose of this review is to assess various purification processes for the production of ultra-pure gallium and to critically examine its applications in the optoelectronics industry. Through this research survey, it is found that zone refining of the zone melting process stands tall over other methods in purifying materials even up to 13N. Hence, scientists are adopting detailed mathematical models and simulation tools for designing unique zone refining systems for material purification. Current-day technology even adopts intelligence methods such as machine learning, which sheds light on the importance of different zone refining parameters that influence the purification process. Here, the practical aspects of zone refining and how the feedback from the theoretical models or performance prediction through intelligence methods can be effectively incorporated into practice have also been emphasized

The full potential linearized augmented plane wave (FP-LAPW) method is used to compute structural, electronic, and optical properties of III-V semiconductor ternary alloys GaP_1-xSb_x (0≤x≤1) using first-principle calculations within density functional theory. To calculate the ground state parameters of the structure, the energy exchange-correlation Wu-cohen generalized gradient approximation is employed in the wiek2k program. The Tran–Blaha-modified Becke–Johnson (TB-mBJ) pseudopotential is employed in addition to the Wu-Cohen generalised gradient approximation to achieve a precise bandgap. After this, WC-mBJ is used to examine optical properties such as real and imaginary parts of the dielectric constant, and energy loss. This study illustrates the nonlinear dependency on the various Sb compositions by examining the composition impacts on the bandgap, bulk modulus, and lattice constant. Using WC-mBJ, the estimated band structures for alloys GaP_0.75Sb_0.25, GaP_0.50Sb_0.50, and GaP_0.25Sb_0.75 show direct energy bandgaps of 2.008 eV (617 nm), 1.482 eV (836 nm), and 1.055 eV (1174 nm), respectively. As a result, this material system has enormous potential for use in applications spanning the visible to infrared spectrum.

Magnesium and sulfate are a determinant key in CaCO₃ mineralization. However, the works of the literature have failed to provide a clear understanding of how these ions influence the nucleation-growth of CaCO₃ precipitation. Our study uses an electrochemical method, having for principle to impose a dissolved oxygen reduction potential on gold (111) films. This technique that allows the exclusive and controlled crystallization of epitaxial calcite established an ideal system for the study of foreign ions influence. The polymorph, composition and morphology of crystals are characterized using scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDS) and Raman spectroscopy. The results demonstrate that the increase of calcium concentration in calcocarbonic pure solution enhances the nucleation and then the growth of calcite crystals without affecting their morphology and their orientation. However, the magnesium directly modifies the surface morphology of calcite as a consequence of Mg substitution to calcium ions and the inhibitive effect of magnesium is assured by an incorporation mechanism. In the matter of sulfate ions influence, the experimental results indicate that SO₄²⁻ slows down the epitaxial calcite nucleation by substituting itself to carbonate ions preferentially in the center of the crystals facets causing an enlargement of the lattice parameter.

Due to the sensitivity of the electronic structure of semi-metals to small distortions of the crystal lattice, the study of the electrical and galvanomagnetic properties of bismuth films requires taking into account the deformation that occurs in the film-substrate system due to the difference in the thermal expansion of the film and substrate materials. The magnitude of these deformations plays an important role in analyzing the temperature dependencies of the transport properties of charge carriers. The paper presents an experimental study of the magnitude of deformation of bismuth films on various substrates at 300 and 77 K using X-ray diffraction. Changes in the lattice constant $�c$ of crystallites, the trigonal axis of which is perpendicular to the film plane, depending on the substrate material, are obtained. A comparison between the assessment of the deformation of these crystallites in the film plane based on Hooke's law and the difference in the coefficients thermal expansion of the film and substrate materials is made.